The present invention relates to absorbent articles for handling urine such as diapers, training pants, adult incontinence absorbent articles, bed mats, and the like. In particular, the present invention relates to those absorbent articles which store urine by means of either capillary or osmotic pressure.
Absorbent articles such as diapers, training pants, adult incontinence absorbent articles, bed mats, and the like are well known in the art and are frequently used for example for babies, toddlers, incontinent persons, and bed-ridden persons.
For many of the intended use conditions, it is desirable for these absorbent articles to exhibit sustained high acquisition rates. For example, in the field of baby diapers it is desired to acquire the discharged urine at a high rate, most preferably with the speed the urine is discharged from the body. This high absorption rate guarantees that all of the discharged urine is actually acquired into the absorbent article. Otherwise, urine which is not readily acquired may move on the surface of the absorbent article and on the skin leading to prolonged skin contact with urine. In addition, urine not acquired by the absorbent article may run off and result in leakage from the absorbent article.
There are certain usage conditions which require a particularly good acquisition performance of the absorbent article. Frequently, urine is discharged from the body in a direction which is different from the direction of gravity. When such urine comes into contact with an absorbent article, the absorbent article is required to acquire that urine against gravity. For example, when the user of the absorbent article lies on his back the direction of urine discharge is anywhere between horizontal and upwards. Hence, urine which is not immediately acquired into the absorbent article will either drip off from the absorbent article or run down the absorbent article and cause the above problems.
Apparently, the higher the rate of urine acquisition by the absorbent article is the less urine may run off from the topsheet of the absorbent article. More preferably, the liquid acquisition rate of the absorbent article is at least at the 50 percentile of urination speed of the intended uses of the absorbent article. Most preferably, the liquid acquisition rate is at least at the 95 percentile of the intended uses of the absorbent article.
In addition, it is desirable for such absorbent articles to exhibit such high liquid absorption rates even for a plurality of subsequent gushes. For example, in the field of baby diapers the typical usage time span on average covers about four liquid gushes. Of course, it is then desired that the absorbent article also absorbs the fourth gush at a sufficiently high rate.
It is further important that the liquid is acquired by the absorbent article and held with sufficient force to not run out of the absorbent article again. This means that the absorbent article must be able to immediately store the acquired liquid in case it is not directly absorbed by the ultimate storage material.
In the prior art, many of the absorbent articles have not being able to provide sufficiently high absorption rates, and in particular have not been able to provide to absorption rates in the range of urine discharge ranges of the body. Hence, the discharged urine either stayed on the topsheet of the absorbent article thereby causing prolonged skin contact with the liquid or was running off the topsheet of the absorbent article thereby resulting in leakage.
Hence, it is an object of the present invention to provide an absorbent article which overcomes the problems posed by the prior art absorbent articles.
It is a further object of the present invention to provide the absorbent article which exhibits a low liquid drip off in the first gush and preferably also in the fourth gush.
It is a further object of the present invention to provide an absorbent article which exhibits sustained high absorption rates in the first gush and preferably also in subsequent gushes up to the fourth gush.
The present invention provides an absorbent structure comprising a first member for liquid acquisition and liquid distribution and a second member for ultimate storage of the acquired liquid. The absorbent structure of the present invention article has a liquid drip off ratio of less than 50 percent in the fourth gush of 75 ml at 15 ml/s according to the liquid drip off test defined herein. Alternatively, the absorbent structure of the present invention has a liquid drip off ratio of less than 4 percent in the first gush of 75 ml at 15 ml/s according to the liquid drip off test defined herein. Alternatively, the absorbent structure has a liquid drip off ratio of less than 60 percent in the third gush of 110 ml at 22 ml/s according to the liquid drip off test defined herein. Alternatively, the absorbent structure has a liquid drip off ratio of less than 4 percent in the first gush of 110 ml at 22 ml/s according to the liquid drip off test defined herein.
The present invention further provides an absorbent article comprising an absorbent structure according to the present invention.